A number of proposals have been made on high energy density batteries using lithium as the negative electrode active material. Lithium batteries using graphite fluoride or manganese dioxide as the positive electrode active material have been marketed. All these batteries, however, were primary batteries which could not be recharged.
As to secondary batteries using lithium as the negative electrode active material, it was proposed to use chalcogenides (e.g., sulfides, selenides, and tellurides) of titanium, molybdenum, niobium, vanadium, and zirconium as the positive electrode active material. Few batteries have been used in practice because these cells do not always have satisfactory cell performance and economy. Although a secondary battery using molybdenum sulfide as the positive electrode active material was commercially manufactured in the recent years, it still suffered from low discharge potential and overcharge failure. Lithium-containing vanadium oxide of the formula Li.sub.1+x V.sub.3 O.sub.8 wherein x=0.05 or 0.2 is known as a positive electrode active material having a high discharge potential. A secondary battery using this oxide as the positive electrode was proposed in J. Electro. chem. Soc., Vol. 133, No. 12, 2454-2458 (1986). However, this secondary battery experienced a substantial loss of capacity during charge/discharge cycles, as demonstrated by a capacity reduction of about 50% after about 20 cycles. Its life is too short as the commercial battery. There is a need for a stable, reliable lithium secondary battery featuring a high energy density and a long charge/discharge cycle life.